Piano back structure



Sept. 26, 1961 J. MERKEL PIANO BACK STRUCTURE Filed June 24, 1957 FIG.

FIG.

INVENTOR:

LOUIS J. MERKEL @hMPr FIG.

ATTORNEY 3,001,433 PIANO BACK STRUCTURE Louis J. Merkel, 7505 Big Bend Blvd,

Webster Groves. 19, Mo. Filed June 24, 1957, Ser. No, 667,374 2 Claims. (Cl. S P-186) generally to improvements in improved piano This invention relates a piano, and more particularly to an back.

In the usual and conventional upright or spinet piano, a metal frame is utilized to position and hold the string sections that are disposed in different angular relation. The strings comprising each section are subjected to tensional force to place the piano in tune, the tensional force being applied and transmitted directly to the frame. Because there are approximately 230 strings in a piano, there is approximately a total of twenty tons applied to the frame, the force components of which are applied in different directions dependent on the disposition of the string sections.

To relieve this bending stress from the metal frame, a heavy wood structure constituting a back is attached to the frame. The usual back, consists of horizontal top and bottom strips interconnected by separate vertical braces interfitted and glued to the strips. After a short: period of'being subjected to the tremendous bending stresses and strains in many directions, the braces of such a structure bend and warp, and hence place the piano out of tune. In almost all instances, the joints of the braces actually" loosen or separate to such an extentthat the metal frame acts to hold the parts of the back together instead of the back reinforcing the frame as intended. It is an important object of the-present improvements to provide a back that will retain the frame rigidly in place at all' times even when subjected to the above described bending stresses and strains, that will not bend or warp, and thus cooperate with the frame to hold the piano in tune and maintain a rigidpiano frame structure.

An important object is realized by the particular arrangement and disposition of the brace members extending between and interconnecting the top and bottom strip members of the piano back so as to oppose directly the tensional force of each string section.

' Yet another important object is achieved in that the brace members are located so that at least one such'brace member extends substantially .parallel to the strings of each string section, and are located immediately behind and in depthwise alignmentwith such section, whereby to oppose directly the tensional force applied and transmitted to the frame and back by the string sections.

Still another important object is realized in that the back is formed from one solid non-compressible panel in which there are no joints that'can ever come apart.

Another important objective is. achieved by the provision of a piano back that is formed from a panel in which openings are provided to define integral top and bottom strip portions and integral brace portions structurally arranged in the manner suggestedabove to provide the functional results and advantages explained. Other important advantages are achieved in that the piano back is simple and durable in construction, and economical to manufacture and assemble.

The foregoing and numerous other objects and advantages of the invention will more clearly appear from the following detailed description of a preferred embodiment, particularly when considered in connection .with the accompanying drawing, in which:

FIG. 1 is a rear elevational view of the piano showing the piano back; a

- to close the top. of the piano ice FIG. 2 is a fragmentary enlarged view in cross. section as seen in a vertical plane passed transversely through. the piano back along line 2--2 of FIG. 1; and

FIG. 3 a front elevational view of the piano back, showing diagrammatically the string sections.

Referring now to characters of reference to the draw-= ing, and first to FIGS. 1 and 2, the improvements are applied to an upright or spinet piano the usual frame of g which includes side boards 11.

The back assembly of the piano is perhaps best shownin FIG, 2, and includes. the novel back structure. 12;

the construction and function of which will be described. in detail later, extending between and secured to side. boards 11. A lid 13 is attached to the base structure. 12 by. hinge. connections. 14, the lid 13 being adapted and being adapted selec timely to be. raised for access to the. internal parts. Located immediately adjacent and contiguous to base struc' ture 12 is a liner 15, the liner 15 being provided with a top. strip 16 located immediately in front of top strip 17 of base structure 12, and being provided with a lower strip 20 located immediately in front of bottom strip 21'- of base structure 12. The upper and lower portions 16 and: 20 of liner 15 are defined by a large center opening 22.

.A laminated. wrest plank 23 formed of a plurality of. plies is located adjacent and contiguous to the. front. surface of:-the top strip 16 of liner 15. The lower edge. of wrest plank 23 is located above and spaced from the lower edge of'top strip 16 to provide an abutment and seat. for the upper edge of a sounding board 24. The:-

sounding board 24.closes the opening 22 provided. in liner 15, the upper edge. of sounding board 24 seating: against the topportion 16 and the lower portion of sounding' board: 24 seating against the front surface of the:

lower strip 20 of liner 15.

. A metal frame. 25, commonly referred to as a plate, is. located immediatelyin front of and contiguous with the'wrest. plank 23, and immediately in front of sounding board 24. The frame 25 isprovided with a lower boss. portion 26'which engages the lower edge of sounding: board: 24; A plurality of screws 27 are utilized to at-- tachf frame 25. to the other component parts of the. back assembly; For example, some of screws 27 extend through. frame 25, wrest plank 23, the top strip 16 of liner 15 and extend into the top strip-portion 17 of back structure 12; Other screws 27 extend through the lower portion of frame; 25 through the lower edge of sounding board 24, through the bottom strip 26 of liner 15,- and into the bottom strip portion 21 of base structure 12'. Thus it is. seen that the frame 25 is directly connected to andis reenforcedbybase structure 12.

The frame. 25 is utilized to position and retain the various string sections of the piano. As illustrated FIG.- 2', a plurality of tuning pins 30 are located in co- OperatingbQIes' formed in the frame 25, wrest plank 23: and. partly in: liner 16. "A bushing 29 is located about each pin and disposed between the pin and frame so that the tensional force applied to the pin is transmitted 1 along the upper edge defining such section, the strings v 31 of each section being attached to and extending between the tuning pins 30 at the upper edge of the sections, and hitch pins indicated at 35 located at the lower edge of each section. It will be particularly noted that the stnngs 31 of bass string section 32 extend generally in one direction, the strings of tenor string section 33 3 V extend generally in another angular position in depthwise spaced relation to the bass string section 32, and the treble string section extends generally in still another angular position.

7 .To tune the strings 31 of each section 32- 34, the tuning pins 30 are rotated in the conventional manner to loosen or tighten the particular strings. A relativelylarge tensional'. orce is applied to strings 31lthr'ough tuning pins 30 to place the stringsiin tune; This tensional force is transmitted through pins 30 and 35 to the metal frame 25 on which: pins are carried. In view' of the fact that there are approximately 230 strings in a piano, the tensional force transmittedto the frame 25 amounts approximately to 20 tons. As a result of this tremendous bending stress andstrain applied to frame? 25, and in view of the fact that such bending stress is applied at ditferentangles depending .upon theangular. disposition of string sections 32-34,"there is a tendency of themetal frame 25 to bend. Any slight" bending of frame 25 would result in placing the piano out of tune To prevent any bending of metal frame 25,'the frame is attached directly to and reenforced by the heavy back structure 12. n l

' The back structure'12 consists of a laminated panel formed of a plurality of plies as shown best in cross section .in FIG. 2.: This'laminated panel 12 is provided with a plurality of openings 36.which define a horizontal top strip portion 17 and an integral horizontalbottom strip portion 21, and a'plurality of integral in terconnecting brace portions 37, 40 and 41; The openings 36 are located immediately behind the 'opening'22' of liner 15, and hence immediately behind the' sounding board24.-

It will be particularly noted that, there is at least one brace portion which extends'between top and bottom strip portions 17 and 21 in substantially thesame angular direction as each of the string sections32-3'4.

From FIG; 3 it is seen that brace portions 37 are located and extend substantially parallel to and immediately in back of and in depthwise alignment with the strings 31 of bass string section 32. The brace portions 40 are located immediately in back of and in depthwise alignment with tenor string section 33, andiextend substantially parallel to and in the same direction as the strings of such section 33. The brace portion 41 is located immediately behind and depthwise aligned with treble string section 34, and extends substantiallyin the same direction as such section 34. Each .of brace portions 37,

.40 and 41 receive in direct compression theftensional forcetransmitted tothe back structure 12'by therespective string sections 32-34 carried on frame '25.

For convenience, the back structure 12 may be formed to provide hand grips 42 at each side of the piano to:

facilitate moving or lifting.

- Because the brace members 37, 40 -41 are formed integrally with top and bottom strip portions 17 and 21, there are no joints that can become loose, and hence the back structure 12 reenforces the frame 25 at all.

times.

plied to the back structure 12 in' a plurality of-directions:

determined by the angular dispositionof .the string sec- Moreover, the bending ,stresses and strains aptions 32-34' are relieved directly by the cooperating brace portions 37, 40 and 41 arranged in substantially the same angular relation in back of and depthwise aligned with the string sections as described above, where- 5 by to prevent any bending or Warping of the back structure 12. This particular structural. arrangement and construction of back structure 12 prevents frame 25 from bending, and hence holds the piano in tune.

In the piano having the conventional back structure, the upper back corner immediately to the rear of the bass section bends forward because of the tremendous tension placed on the strings of such section. Asa result,

the opposite end of the piano where the treble sectionis located, actually raises off the floor and causesan unbalanced condition. The present piano back structure eliminates or greatlyminimizcs the eifect 0 this twisting force, and hence solves this problem.

' Although the invention has been described by'makin'g' detailed reference to a single preferred embodiment, such detail isto be understood to be in an instructive, rather than in any restrictive sense, many variants being pos;

sible within the scope of the claims hereunto appended. I claim as my invention: l.'A piano back for a piano having a plurality of string sections each of which is comprised of a pluralityof substantially parallel strings and each of which is arranged in a difierent angular relation, the'pianoback comprised of a panel havingopenings therethrough, said: 1 openings defining top and bottom strips, and defining a 30 plurality of braces extending between said strips andconnected integrally therewith, at least one brace 1 extend-- ing parallel to and disposed directly behind in depthwise alignment with the strings of each of the .string sections in the piano to which the back is attached.

-2.- In a piano, a piano back, a string plate secured to said back, a plurality of string sections relating to bass, tenor or treble attached to and tensioned on said string plate, saidstring sections being disposed in different angular relation, whereby to transmit'the tensional force of each section to said string plate and said piano back indifferent directions, the piano back consisting of an integral panel having openings therethrough, said openings de'fining a top and a bottom strip portion, and defining a plurality of brace portions integrally connecting said strip portions, at least one of said brace portions extending longitudinally parallel to the strings of each one of said string sections and located immediately behind and in depthwise alignment with such section, whereby said brace portions directly oppose the tensional force applied to the piano back by said string sections so as to maintain the piano in tune;

References Cited in the meet this patent UNITED STATES PATENTS 

